JP2735389B2 - Covered stent and stent delivery device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a stent that can be used in a conduit in an animal or human body. The invention also relates to an apparatus for delivering a stent to a treatment site. The stent has a specific diameter under no load, but can be compressed to a smaller diameter by radially compressing the stent or pulling away from the end of the stent. Having a tubular body. This feature
Provided is a stent which is particularly effective for mechanical conduit transplantation into a bile duct, a respiratory tract, an esophagus, a blood vessel and the like. This stent feeder
A first tube having a central lumen for receiving a guidewire;
A flexible hose folded over itself to removably surround the first tube. The stent is positioned around the first tube and is held in a radially contracted state by a flexible hose. The stent is thus introduced percutaneously into the body vessel at the treatment site and delivered to the treatment site. The stent is deployed by winding a flexible hose away from the stent so that it can self-deploy in the radial direction. Once the stent is deployed, the stent delivery device can be pulled.

Conventional radially self-expanding stents have an open mesh structure. After positioning such a stent, tissue grows through the voids between the wires of the stent. In many applications, such a phenomenon is
There is no penalty for the efficacy of the stent. In many cases, it is undesirable for the tissue to grow. This is because holding the stent in place will hinder the movement of the stent.

However, in some applications it is disadvantageous for the tissue to grow in. For example, if the stent must be placed in a body conduit where the tumor is growing inward to maintain the patency of the body passageway, the tumor will grow through the stent This limits the effectiveness of the stent. Tumor growth completely blocks the body's conduits. In addition, such tumor growth will permanently "lock" the stent in place.
It is undesirable in applications where the ability to remove a stent is considered.

Conventional radially self-expanding stent delivery devices are implemented entirely according to the purpose for which they are intended.
A typical conventional delivery device has a movable annular member that forces the stent into a contracted state with an inner catheter. The annular member is removed from contact with the stent so that the stent can be deployed. In some arrangements, the annular member folds itself to form a double wall portion. However, such prior art delivery devices are not totally effective in delivering a stent to a treatment site. For example, as the walls move past each other, friction between the walls of the double wall portion of the movable annular member makes it difficult to remove the annular member from the stent. One way to minimize this problem is to apply pressure between the walls of the annular members to move the walls of the annular members away from contact with each other. However,
This makes operation of the feeder difficult. The operator of the feeder must continuously monitor the pressure to ensure that the pressure is maintained in a certain range. If the pressure is too low, the friction cannot be overcome. If the pressure is too high, the feed device will burst.

EP 0481365 describes a device for expanding a stenosis in a body vessel. The device is formed from a shape memory alloy that expands radially above ambient temperature and below body temperature. DE 4022956 describes intraluminal rails. This rail consists of wires formed in a basket surrounded by an electrically insulated sheath and removably surrounding the inflatable balloon, where the circumferentially extending spacing is freely maintained Have been. This spacing is formed to be inflatable in a mesh and peripheral direction by regular repetition and joining of the sheath of adjacent wire portions so that the sheath promotes expansion by applying a voltage to the wire. Therefore, it can be softened at least once by heat. DE 3918736 discloses a metallic grid stent for permanent expansion of arterial stenosis, which is coated with a thin layer of polytetrafluoroethylene. WO 88/01924 discloses a gripping means made of a flexible material consisting of an inner wall and an outer wall, each having an annular area in the middle. GB 2195257 discloses a device for implantation by insertion of a substantially tubular, radially expandable prosthesis. The device comprises a combination of such a prosthesis and a flexible probe having a means for holding the prosthesis in a central position in a radially contracted state and releasing the prosthesis in a desired position, The means for holding the prosthesis comprises a hose concentrically surrounding the probe and radially surrounding the prosthesis to form a chamber, the probe providing a supply of liquid ejection medium to the other end. The probe has at least one radial opening that opens into the prosthetic compartment to remove gas from the prosthetic compartment prior to implantation. It is characterized in that the prosthesis chamber can be washed out.

Accordingly, it would be desirable to provide a stent that maintains the patency of a bodily conduit and reduces tissue ingrowth through the stent.

It is also desirable to provide a stent so that it can be removed in a body conduit.

It is further desirable to provide a stent delivery device that can deploy a stent at a treatment site with little difficulty.

SUMMARY OF THE INVENTION These and other objects are achieved by the cover stent of the present invention. The cover stent has a flexible annular body, the diameter of which can be varied by axial compression of the ends of the body with respect to each other by radial compression of the stent. The cover stent assumes a certain diameter when it is in an unloaded state without external forces. The body is comprised of several discrete, rigid, but flexible threaded members, each of which extends helically to the body's centerline as a common axis. Many such thread members have the same winding direction but are axially displaced with respect to one another. The remaining thread members have opposite winding directions to the previously described thread winding direction and are axially displaced from one another. Thus, each thread member intersects with a number of other thread members in a blade shape.

Also, the stent is covered with a continuous, flexible polymeric material, preferably of silicone rubber. The cover prevents tissue from growing through the stent when the stent is implanted in a body vessel. This film is preferably applied to the stent by dip coating the stent in a bath of silicone rubber and an organic solvent. The thickness of the film can be controlled by the silicone rubber and the organic solvent in the tank and the number of dip coatings performed on the stent.

The stent control device has an elongated, flexible inner tube with a central lumen for receiving a guidewire. The stent is
It is placed in this tube in a radially contracted state for delivery to the treatment site. A flexible hose surrounds the tube and folds itself to form a double wall portion. This double wall portion surrounds and closes the stent in a radially contracted condition with the vessel. To allow the flexible hose to move easily away from the stent,
The portion of the hose that itself contacts the heavy wall portion has lubricity. This lubricating property can be achieved by placing a lubricating coating on the surface of the hose that itself contacts the double wall portion of the hose, by injecting the lubricating fluid into the gap between the walls of the double wall portion, or by natural lubrication. This is achieved by forming a flexible hose from a lubricating material. This facilitates use of the stent delivery device of the present invention and simplifies deployment of the stent.

When attempting to deploy the stent at the treatment site, the flexible hose is first unwound proximally to expose the distal end of the stent. This allows the operator of the stent to first properly align the delivery device with the distal portion of the body conduit. When proper alignment is achieved, the operator can continue to wind the flexible hose proximally so that the stent is fully visible, and radially self-engage the stent to engage the wall of the conduit. Can be expanded.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings, in which like parts are designated with like numerals throughout. Would.

FIG. 1 is a perspective view of a cover stent of the present invention, clearly showing the blade shape of the thread member.

FIG. 2 is a perspective view of the cover stent of the present invention in a radially contracted state that clearly shows the blade shape of the thread member.

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG.

FIG. 4 is a detail view of a portion of the stent of the present invention shown without a cover to show the blade shape of the thread member.

FIG. 5 is a detailed view of a portion of the stent of the present invention shown without a cover to show the braid shape of the thread member.

FIG. 6 is a cross-sectional view of a portion of a covered stent of the present invention showing a flexible polymer matrix disposed along the outside of the stent.

FIG. 7 is the same partial cross-sectional view as FIG. 6 with the flexible polymer disposed along the inside of the stent.

FIG. 8 is a side view of a stent delivery device of the present invention having a cover stent loaded therein.

FIG. 9 is an enlarged view of a region drawn by a reference numeral 9 in FIG.

FIG. 10 is an enlarged side view of an area circled by reference numeral 10 in FIG.

11 to 14 are side views of the stent delivery device and the distal portion of the cover stent at various stages of the stent deployment operation of the body container.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows an example of a cover stent 10 of the present invention in an unloaded state. The cover stent 10 is in the form of a cylindrical annular body. The stent 10 is formed by a number of individual thread members 11. Some of these members extend helically in one direction that is axially displaced relative to one another with the central longitudinal axis of the stent 10 as a common axis. The other members extend helically in opposite directions and are axially displaced with respect to one another having a central longitudinal axis as a common axis. Accordingly, the thread members 11 extend in two directions and intersect with each other while being knitted with each other.

The thread members 11 of the stent 10 are preferably arranged symmetrically such that the same number is used in each of the winding directions. The number of thread members required is a function of the diameter of the stent 10 at no load. In a stent having a diameter of 10 millimeters, 24 thread members are used. The thread member 11 is spirally wound around a cylindrical mandrel. One set of thread members is wound in one direction, and the other set of thread members is wound in the other direction.

The thread member 11 must be maintained in tension. Insufficient tension causes the individual thread members to deviate from their original shape and loose the braid or knit structure of the stent. When the thread members 11 are properly tensioned, a slight compression is formed in the overlapping thread members at each intersection. See FIG. 4 and FIG. Each thread member deforms so that it bends over the other thread members and surrounds a portion of the other thread member. Typically, only the portion of each thread member at the top of the radially intersecting thread members bends. These imprints or saddles tend to secure them together at the intersection of the thread members. This maintains the stent shape without requiring welding or other joining of the thread members 11 at the intersection of the thread members. In addition, this allows the annular blade to be cut to the appropriate length to produce a stent of the desired length.

To improve the radial stability of the stent, the axial angle between the intersecting thread members is about 90 °
The above is preferable, when the stent is in an unloaded state, 100 °
It is preferable that it is above. The greater the angle, the more stable the stent under external pressure.

The thread members 11 forming the stent 10 can be made from various polymers, for example, biocompatible and flexible rigid materials such as Kelver ™, and metals such as stainless steel. Other materials include alloys based on cobalt, chromium, nickel and molybdenum, with the remaining alloy being iron. Further, the thread member 11 is formed of a core and a tubular case surrounding the core. This shape can improve the impermeability of the stent 10. For example, the core can be manufactured from impermeable tantalum, while the case is based on cobalt, such as the alloy marketed under the trade names "Elgiloy", "Finox" and "MP35N". Metal. Such clad composite thread members for use in the manufacture of stents are described in WO 94/16646, which is incorporated herein by reference.

The diameter of the stent 10 can be deformed by radially compressing the stent 10 or moving the ends of the stent 10 axially with respect to each other. FIG. 2 shows how the diameter of the stent 10 according to FIG. 1 can be reduced by moving its ends away from each other in the direction of the arrows. Stent 10
Must be engaged against the wall of the body vessel where the stent is placed at a certain pressure to remain fixed, so the radially contracted stent diameter is
It must be smaller than the diameter of the freely deployed stent 10.

The stent 10 is covered by a matrix 15 of a flexible polymeric material such as silicone rubber, polyurethane or Teflon. Other flexible and biocompatible polymers can also be used. Preferably, silicone rubber is used. Matrix 15 is
Take the form of a film or knit or woven cover.

The matrix 15 is preferably applied to the stent 10 by dip coating. Liquid silicone rubber is mixed with an organic solvent, preferably xylene, to fluidize the silicone rubber. In the case of a stent having a diameter of 10 mm, the angle between the thread member and the blade is 110 °, and when the stent is supported only at its end by the silicon rubber and xylene bath, 27% with respect to xylene
It is preferred to use a ratio of silicone rubber of When using this configuration, one dip coating is required to complete the cover stent 10. 20 diameter
For mm stents, the thread member and blade angle is 110 °, and if the stent is supported by silicon rubber and xylene bath only by the inner mandrel, use a ratio of 18% silicon rubber to xylene. Is preferred. With this configuration, three to five dip coatings are required to complete the cover stent 10.

Additional coats beyond those described above can also be applied. However, if too many coats are used, the resulting stent will be less flexible,
It becomes difficult to load the stent on the delivery device and deploy the stent at the treatment site. A coating thickness of about 0.010 cm (0.004 inches) has been found to be preferred.
Alternatively, if it is desired that the matrix 15 be more flexible, the matrix 15 can take the form of a knit or woven cover.

The stent 10 can be dip by supporting the ends of the stent 10, by using an outer mandrel, or by using the inner mandrel to support the stent 10 when immersed in a bath of silicone rubber and xylene. Can be coated. When dip-coating the stent 10 by supporting the ends of the stent 10, the silicone rubber extends only between the gaps between the thread members 11 so that the thread members do not have excess silicone rubber outside or inside the stent 10. Surround 11 See FIG. 3 and FIG. When the stent 10 is supported by the outer mandrel, the silicone rubber coating tends to extend outwardly of the thread members 11 forming the stent 10. See FIG. When the stent 10 is supported by the inner mandrel, the silicone rubber tends to extend inward of the thread members 11 forming the stent 10. See FIG. Preferably, the stent 10
Should be supported at the end or by the outer mandrel during the dip coating process. The matrix created by this process tends to be stronger and more resistant to tearing so as to better prevent tissue growth through the gap between the thread members 11 forming the stent 10.

While the dip coating process described above is the preferred method of covering the stent of the present invention, the matrix 15
Can be applied by injection molding or other methods such as spraying the coated stent 10 with a polymeric material.

The stent 10 is placed on a stent delivery device 20 that delivers the stent in a radially contracted state to a treatment site in a body conduit. The stent 10 is carried by the distal portion of the delivery device 20. The proximal portion of the feeder 20 remains outside the body for operation by the operator.

Feeder 20 has an elongated inner tube 30 having an axially extending lumen 35. The distal end portion of the inner tube 30 is flexible and can be made from nylon or other suitable flexible biocompatible polymer material. At its distal end, the inner tube 30 is provided with a head 31 through which a lumen 35 is continuous. The head 31 acts to facilitate insertion of the delivery device through a narrow opening in the body conduit. The proximal portion of inner tube 30 is preferably made of stainless steel or some other suitable rigid alloy. The proximal end of the distal portion of the inner tube 30 can be made in a conventional manner by using a standard adhesive.
Attached to the distal end of the 30 proximal portion.

Proximal tube 50 coaxially surrounds the proximal portion of inner tube 30. Preferably, the proximal tube 50 is formed from polyurethane. The proximal end of the proximal tube 50 is connected to a valve body 40 having a side port 41. An extension tube 45 extends from the side port 41 to the opening 42. This configuration allows the fluid to be extended
It can be injected through 45 between the proximal tube 50 and the inner tube 30.

A movable hose 55 surrounds the distal portion of the inner tube 30. The hose 55 is wound on itself to form a double wall.
The proximal end of the inner wall 56 of the double wall portion is directly connected to the inner tube 30. The proximal end of the outer wall 57 of the double wall section is the proximal tube
It is connected to the outer surface of the 50 distal part. These connections are achieved by conventional means, such as a standard adhesive. This configuration allows the hose 55 to expose the stent 10 located at the distal portion of the inner tube 30. By moving the valve body 40 in the proximal direction, the outer wall of the hose 55 slides on the inner wall 56 in the proximal direction. This allows the inner wall 56 to "roll back" from the stent 10. To facilitate the transfer of the hose 55 from the stent 10, at least that portion of the inner wall that contacts the outer wall 57 in the area where the hose 55 is bent to form a double wall portion must be smooth.

Lubricating properties are achieved by applying a lubricating substance to the surface of the hose 55 and spraying a lubricating liquid between the inner wall 56 and the outer wall 57 or forming the hose with a slippery material such as Teflon. Can be achieved.

In a preferred embodiment, at least the surfaces of the inner wall 56 and the outer wall 57 facing each other in the part of the double wall are coated with a smooth hydrophilic coating. Preferably, the trade name 20
Use a hydrophilic coating manufactured and sold by Hydromer at 18-M. Other materials include polyethylene oxide and hyaluronic acid. The hydrophilic coating becomes smooth when wet, so that the outer wall 57 moves over the inner wall 56 when the inner wall 56 and outer wall 57 of the double wall portion of the hose 55 are moved.
And the friction between them is reduced. This facilitates removal of the double wall portion of the hose 55 from the stent 10.

Preferably, a hydrophilic material is added to the hose 55 during assembly of the feeder 20. To properly bond the hydrophilic material to the hose 55, the materials used to make the hose 55 include:
Must match the hydrophilic material used. hose
The material forming 55 has been found to be a polyurethane product. In particular, the mixture of 65D and 75D provides sufficiently soft flexibility that the hose 55 can be wound on itself consistent with the hydrophilic material. Preferably the mixture is 50%
Manufactured from 65D and 50% 75D polyurethane.

During assembly of the feeder 20, one side of the hose 55 is
After connecting the (outer wall 57) to the proximal tube 50, it is coated with a hydrophilic material. First, isopropyl alcohol is applied to one side of the hose 55 to clean the surface and remove the wax film resulting from the polyurethane plasticizer. Next, the same side of the hose 55 is coated with a hydrophilic material.
The surface of the hose 55 must be flushed with alcohol for about 30 seconds. Similarly, the surface of surface 55 must be flushed with a hydrophilic coating for about 30 seconds. This technique allows the inner wall 56 to rewind the hose 55 with minimal friction when the hydrophilic material gets wet.
And the outer wall 57 has been found to accumulate sufficient hydrophilic material.

When the feeder 20 is assembled and ready for use, the hose 55 passes through the extension tube 45 and beyond the proximal tube 50
The hydrophilic coating is wetted with saline by injecting the solution into the gap between the inner wall 56 and the outer wall 57 of the heavy wall portion. Excess liquid exits through a hole 59 formed toward the distal end of the double wall portion of hose 55. Similarly,
Instead of applying the lubricating hydrophilic material as described above to the hose 55, a lubricating liquid such as polyethylene glycol is injected into the gap between the inner wall 56 and the outer wall 57 of the double-walled portion to form a hose.
55 can provide lubrication properties.

The stent 10 is placed in a radially compressed relationship surrounding the outer end of the inner tube 30 for delivery of the stent to a treatment site in a body conduit. The stent 10 is confined to the inner tube by a double wall portion of the hose. It is important that the stent 10 not be too tightly confined in the inner vessel. Hose 55
Can be used to hold the stent 10 in place.
Ten must apply enough force. Hose 55-2
The portion of the heavy wall can be removed from the surrounding surrounding the stent 10 by pulling the valve body 40 and the proximal tube 50 in a proximal direction. The double wall portion exposes the stent 10. No sliding occurs between the stent 10 and the inner wall 56 that contacts the stent 10. With the movement of the double wall portion toward the proximal end, the distal end of the stent 10 is exposed radially to engage the wall of a body conduit. See FIG. The double wall portion of the hose 55 continues to move in the proximal direction, and the stent
Is exposed and expands radially until it engages the wall of a body conduit. See FIG.

Lumen 35 is used to allow the stent delivery device to follow a guidewire (not shown) that has been previously inserted percutaneously into a body conduit. The lumen 35 of the inner tube 30 introduces a contrast liquid into the area around the distal end of the feeder so that the position of the feeder 20 can be easily detected, for example by using X-ray technology. Can be used for

Accordingly, a cover stent is provided that maintains the patency of a bodily conduit and reduces tissue growth through the stent. In addition, a stent delivery device is provided that minimizes friction during component movement and allows deployment of the cover stent at the treatment site with minimal difficulty. Those skilled in the art should understand that the described embodiments are for purposes of illustration, not limitation, and are limited only by the following claims.

Claims (18)

(57) [Claims] 1. A radially expandable stent (10), extending in a helical shape along a centerline of the stent;
At least one first thread member (11) having a first winding direction, extending in a helical shape along a centerline of the stent;
At least one traversing the at least one first thread member (11) and having a second winding direction to form a plurality of gaps between the first thread members (11).
Two second thread members (11), the first and second thread members (11) and (1) defining an inner surface of the stent and an outer surface of the stent.
1), surrounding and surrounding each of the first and second thread members, and closing a gap between each of the first and second thread members (11). A matrix (15), which is integral with the stent and is radially expandable with the stent, and covers the stent and reduces inward elongation of tissue therethrough. A flexible matrix (15) comprising: a radially expandable stent (10) comprising: 2. The radially expandable stent of claim 1, wherein the polymeric material is silicone rubber.
0). 3. The stent of claim 1, wherein the polymeric material is polyurethane.
0). 4. The polymer material is Teflon (trade name)
A radially expandable stent (10) according to claim 1, wherein the stent is: 5. A matrix (15) for closing said gap, wherein said matrix (15) has a thickness of about 0.5 mm.
A radially expandable stent (10) according to any of the preceding claims, having a thickness of 0.004 inches (010 cm). 6. The method according to claim 1, wherein said matrix of polymeric material covers the outer surface of the stent.
The radially expandable stent of claim 10, (10). 7. The method according to claim 1, wherein the matrix of polymeric material covers the inner surface of the stent.
The radially expandable stent of claim 10, (10). 8. A device (20) for deploying a radially expandable stent, the device comprising a distal portion and a proximal portion, wherein at least the distal portion is flexible. A) a radially expandable stent (10), at least one first thread member extending in a helical configuration along the centerline of the stent and having a first winding direction; And extending in a helical configuration along the centerline of the stent and having a second winding direction to traverse the first thread members and form a plurality of gaps between each thread member. At least one second thread member, wherein the first and second thread members together define an inner stent surface and an outer stent surface, and may comprise a polymeric material. A flexible matrix includes a first thread member and a second thread member. Surrounding and enclosing each of the red members and closing the gap between each of the first and second thread members, the matrix being integral with and radially associated with the stent; A radially expandable stent (10) surrounding the portion of the elongate inner tube (30), which is inflatable and has reduced elongation of tissue over and over the stent; A proximal tube (50) coaxially disposed about the proximal portion of the (30), a portion of the distal portion of the elongated inner tube (30) and the stent (1).
Hose (55) surrounding 0) and maintaining the stent (10) in a radially contracted state over the elongated inner tube (30)
Wherein the inner wall is folded over to form a double wall portion having an inner wall and an outer wall, wherein the inner wall is an elongated inner tube.
A hose (55), the outer wall of which is connected to the proximal tube (50), and a lubricating coating on at least one surface of the inner or outer wall of the double wall portion of the hose (55). A device for deploying a radially expandable stent (20). 9. The stent deployment device according to claim 8, wherein the polymer material is silicone rubber. 10. The stent deployment device according to claim 8, wherein the polymeric material is polyurethane. 11. The stent deployment device (20) according to claim 8, wherein the lubricating coating is hydrophilic. 12. The stent deployment device according to claim 8, wherein said lubricating coating is polyethylene oxide. 13. The stent deployment device according to claim 8, wherein the lubricating coating is hyaluronic acid.
0). 14. A matrix of said polymeric material (15).
9. The device (20) for deploying a stent according to claim 8, wherein the device has a thickness of about 0.004 inches. 15. A device (20) for deploying a stent (10) that is radially expandable in a body conduit, the device having a distal portion and a proximal portion, wherein at least the distal portion is flexible. An elongate inner tube (30), a proximal tube (50) coaxially disposed about a proximal portion of the elongate inner tube (30), and a distal portion of the elongate inner tube (30). A hose (55) formed of a lubricating material surrounding a portion thereof, wherein the hose (55) is folded over itself to form a double wall portion having an inner wall and an outer wall, the inner wall being an elongated inner tube (30). ), A hose (55) whose outer wall is connected to a proximal tube (50), and a radially expandable stent (10), which is helically shaped along the centerline of the stent. A first thread member extending and having a first winding direction surrounding a portion of the elongated tube; Extending in a helical shape along the centerline of the thread and having a second winding direction to traverse the first threaded member and form a plurality of gaps between each of the first threaded members. A second thread member, a first thread member and a second thread member defining an inner surface of the stent and an outer surface of the stent, and each of the first thread member and the second thread member. A matrix surrounding and surrounding, and closing a gap between each of the first and second thread members, the matrix being integral with and radially expandable with the stent. A matrix covering the stent and reducing inward stretching of tissue therethrough, the stent being radially expandable surrounding a portion of the elongated tube; Body consisting of Apparatus for deploying a stent (10) in the conduit is expandable in a radial direction (20). 16. The device (20) for deploying a radially expandable stent (10) in a bodily conduit according to claim 15, wherein the lubricating material is Teflon. 17. A matrix of said polymeric material (15).
16. An apparatus (20) for deploying a stent (10) that is radially expandable in a body conduit according to claim 15, wherein is a silicone rubber. 18. A matrix of said polymeric material (15).
16. The device (20) for deploying a radially expandable stent (10) in a body conduit according to claim 15, wherein is a polyurethane.